Photocurable materials having an acrylic group as a radical polymerizable group have been widely used in electrical and electronic members, building materials, optical components, medical materials, and the like. In particular, there are a lot of use applications that require high strength of photocured products to be obtained by using photocurable materials. A photocured product having high strength can be generally obtained by increasing the number of radical polymerizable groups per volume. As a technique for increasing the number of radical polymerizable groups, a material having a plurality of acrylic functional groups and/or a material having a rigid skeleton may be used.
However, a photocured product obtained by using the above technique has high strength, while the photocured product has low toughness and the photocured product is brittle. Thus, the product has problems in that cracks occur due to shrinking upon curing or impact and/or the photocured product is not formed in a desired shape/dimension due to shrinking upon curing. Further, in association with these problems, a problem arises in that the photocured product is peeled off from a base material to which the photocured product is intended to be fixed or attached.
In order to solve these problems, it is known that a scheme in which a plasticizer is added to a photocurable material, to increase toughness of a photocured product having high strength to be obtained, or a scheme in which a plasticizer is added to a photocurable material, to impart flexibility to the photocured product having high strength to be obtained. However, when the plasticizer is used, a problem arises in that the plasticizer is leaked (bled out) on the surface of the photocured product. This causes a problem in decreased stability of the photocured product, for example, a problem in decreased biological safety in a case where the photocured product is used as a medical material.
A polyrotaxane has properties that, when a cyclic molecule constituting the polyrotaxane moves on the linear molecule, viscoelasticity, low compression permanent strain, and the like occur in a crosslinked body of polyrotaxanes, a crosslinked body of a polyrotaxane and a polymer other than the polyrotaxane, and the like. For this reason, the polyrotaxane is expected to be applied to various use applications, and thus, research and development thereof have been actively conducted.
For example, Patent Document 1 discloses a photocrosslinkable polyrotaxane, wherein a cyclic molecule of a polyrotaxane has a photopolymerizable group at side chain terminals of a lactone or carbonate polymer, a cured product formed by using the polyrotaxane, and the like. In addition, it is disclosed that the cured product has properties such as scratch resistance, folding resistance, and low hysteresis loss. However, the cured product disclosed in Patent Document 1 is a cured product having flexibility, and there is no disclosure on a cured product with high strength and high hardness.